I find the new operator a bit confusing. My understanding now is that
new ClassName(...)
is to make an instance and call the Class' constructor. But what does new do when initiating an Array? For example, I feel the two new operators below are different, but can't explain clearly.
Employee[] staff = new Employee[3];
staff[0] = new Employee(...);
Are there any difference?
Thanks.
new Employee[3] creates an array that can hold references to 3 Employee instances. Each of them is initialized to null. staff[0] = new Employee(...); creates an Employee instance and assigns its reference to the first index of the array.
Employee[] staff = new Employee[3];
Is initializing your array of Employees with 3 "places" which can hold references to your Employee objects.
That means it reserves 3 times the space needed for one object/instance of your Employee class (e.g. 10byte) in the RAM (=> 30 byte).
But your array is initalized with "null".
While staff[0] = new Employee(...); is creating a reference to your newly created object of type Employee.
int[] arr = new int[10]; // allocates memory for 10 integers For more info: docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.htmlWhen you call the class' constructor, an instance (object) of that class is created. The "new" keyword is what tells the compiler to create an object. An array is a class and you make objects of type Array of SomeClass. You need to use the keyword "new" because you are still creating an object.
Employeeobject.staff[0]is of typeEmployee.